Microphones outside the ear detect sounds and send them to a speech processor, which analyzes the information and transmits it to a receiver where it is converted into electric impulses. The implant sends those impulses directly to the auditory nerve. With training, the brain learns to recognize these impulses as useful sound information.

The CSU device operates very similarly except electric impulses are sent via Bluetooth to a retainer-like mouthpiece packed with electrodes. When users press their tongue against the device, they feel a distinct pattern of electric impulses as a tingling or vibrating sensation.

The idea is that, with training, the brain will learn to interpret specific patterns as words, thus allowing someone to “hear” with their tongue.